The present invention relates to an image recording apparatus, and more particularly, to the apparatus in which an unexposed zone of a photosensitive sheet positioned at downstream side of an exposure zone is fed back to an upstream side thereof for using the unexposed zone for a next exposure operation.
In a conventional image recording apparatus, a rolled photosensitive sheet wound over a sheet roll core is taken up by a takeup shaft through an exposure portion, a pressure developing unit, and a separation portion. In the exposure portion, the photosensitive sheet is subjected to light exposure for forming a latent image thereon, and in the pressure developing unit, the photosensitive sheet carrying the latent image thereon is superposed with a cut developer sheet and these sheets are pressed together for forming a visible image on the developer sheet. Further, at the separation portion, the photosensitive sheet is separated from the developer sheet, and the light exposed photosensitive sheet is taken up by the takeup shaft.
In the conventional apparatus a pair of feed rollers are provided at a position between the exposure portion and the pressure developing unit for nippingly feed the photosensitive sheet toward the pressure developing unit at a constant speed. The photosensitive sheet may be a microcapsule sheet in which an immense number of microcapsules encapsulating therein chromogenic material and photosensitive resin, etc. are coated over a substrate to provide a photosensitive layer.
In this type of the conventional apparatus, an area of the photosensitive sheet at a position between a trailing edge portion of the light-exposed photosensitive sheet and a leading edge portion of a newly light exposed portion does not serve for the formation of the latent image. That is, this area is merely wound over the takeup shaft. Therefore, entire area of the photosensitive sheet cannot be effectively used.
To avoid this drawback, after separation of the developer sheet from the photosensitive sheet, the unexposed zone of the photosensitive sheet positioned at downstream side of the exposure portion is fed back to the upstream side thereof by reversely rotating the rolled photosensitive sheet, so that the unexposed zone subsequent to the exposed zone can be used for the exposure, to thereby minimize sheet wasted area.
However, since the pair of feed rollers are continuously nipping the photosensitive sheet, the unexposed area may be damaged by the nipping pressure, that is, the microcapsules may be ruptured, or the photosensitive layer may be damaged. If such damaged zone is used for the next exposure operation, resultant output image may be degraded, and clear output image may not be obtainable.
Further, during the reversal feeding of the photosensitive sheet, if the unexposed area is subjected to accidental light irradiation, this area may become unavailable for the next exposure operation.